How many consumers Kafka can handle?

Kafka can at max assign one partition to one consumer. If there are more number of consumers than the partitions, Kafka would fall short of the partitions to assign to the consumers. Not all the consumers of the group would get assigned to a partition and hence some of the consumers of the group would be idle.

How many clients can Kafka have?

1 Answer. Some Kafka users such as LinkedIn have reported in the past that a single Kafka broker can support ~10K client connections. This number may vary depending on hardware, configuration, etc.

How many consumers can subscribe to a topic?

one consumer
A consumer can be assigned to consume multiple partitions. So the rule in Kafka is only one consumer in a consumer group can be assigned to consume messages from a partition in a topic and hence multiple Kafka consumers from a consumer group can not read the same message from a partition.

How do you check the number of consumers in Kafka?

A ‘-list’ command is used to list the number of consumer groups available in the Kafka Cluster. The command is used as: ‘kafka-consumer-groups. bat -bootstrap-server localhost:9092 -list’.

Can Kafka have multiple consumers?

While Kafka allows only one consumer per topic partition, there may be multiple consumer groups reading from the same partition. Multiple consumers may subscribe to a Topic under a common Consumer Group ID, although in this case, Kafka switches from sub/pub mode to a queue messaging approach.

How do I run multiple Kafka consumers?

To run multiple consumers in the same group in one application, you will need to run each in its own thread. It is useful to wrap the consumer logic in its own object and then use Java’s ExecutorService to start multiple threads each with its own consumer.

What are Kafka consumers?

Kafka consumers are typically part of a consumer group . When multiple consumers are subscribed to a topic and belong to the same consumer group, each consumer in the group will receive messages from a different subset of the partitions in the topic. Consumer C1 will get all messages from all four T1 partitions.

How many consumer groups can Kafka have?

In Kafka, there is no explicit limit on the number of consumer groups that can be instantiated for a particular topic. However, you should be aware that the more the consumer groups, the bigger the impact on network utilisation.

Can one Kafka consumer subscribe to multiple topics?

Apache Kafka allows a single consumer to subscribe to multiple topics at the same time and process both in a combined stream of records.

How do you list consumers in Kafka?

Get the list of consumer groups for a topic. Use kafka-consumer-groups.sh to list all consumer groups. Note that the below command will list all the consumer groups for all topics managed by the cluster.

How many consumer groups are there in Kafka?

3 Answers. In Kafka, there is no explicit limit on the number of consumer groups that can be instantiated for a particular topic. However, you should be aware that the more the consumer groups, the bigger the impact on network utilisation. As it was said above, up to few thousands, should be okay.

How consumer group works in Kafka?

Kafka consumers belonging to the same consumer group share a group id. The consumers in a group then divides the topic partitions as fairly amongst themselves as possible by establishing that each partition is only consumed by a single consumer from the group. The messages are broadcast to all consumer groups.

Can multiple Kafka consumers read the same message?

If you have two Kafka consumers with different Group Id they will read all 12 partitions without any interference between each other. Meaning both consumers will read the exact same set of messages independently. If you have four Kafka consumers with different Group Id they will all read all partitions etc. I found this image from OReilly helpful:

How many partitions can a Kafka consumer read at once?

If you have 4 Kafka cosnumers with the same Group Id, each of them will all read three different partitions etc. But when you set different Group Id, the situation changes. If you have two Kafka consumers with different Group Id they will read all 12 partitions without any interference between each other.

What is a consumer group in Kafka?

Conceptually you can think of a consumer group as being a single logical subscriber that happens to be made up of multiple processes. In simpler words, Kafka message/record is processed by only one consumer process per consumer group. So if you want multiple consumers to process the message/record you can use different groups for the consumers.

Why are topics in Kafka not queues?

4 Kafka topicsare not queues, because once a message is consumed from a topic, it stays there(unless its lifetime has expired) and the offsetmoves to the next, whereas for a queue, once a message is consumed, the message is removed from that queue. Ordered sets is also by partitionsonly. – jumping_monkey Jun 5 ’20 at 14:16